Trophic effects of vanadium on beta-cells of STZ-induced insulin dependent diabetic rats & evidence for long-term relief of diabetes mellitus.

The effects of one year combined vanadium and insulin treatment (VIT) on blood glucose levels of insulin dependent diabetic (IDD) rats were studied. Rats made diabetic by an i.v. injection of 55-60 mg/kg streptozotocin (STZ), divided into two groups and treated with a low dose of NPH insulin (2-4 U/rat) for two months to survive from hyperglycaemic shock. In group A, hyperglycaemia ameliorated during one year by increasing the daily dose of insulin to 8.2 +/- 0.4 U/100 g (IT) and in group B by switching over to hydrated vanadium solution (1 mg/ml vanadyl oxide sulphate pentahydrate in drinking water; VIT). The results of the study indicated that one year VIT regenerated new beta-cells, and relieved diabetes both during treatment and after withdrawal. However, one year IT showed no trophic effects on the destroyed beta-cells, hence no improvement in the glycaemic status of the animal was seen after withdrawal. The action of VIT was such that in group B normoglycaemeia persisted in 90 per cent of diabetic rats two weeks after insulin withdrawal. But in the same group, 45 days after combined vanadium and insulin withdrawal blood glucose was normal in 60 per cent of the rats, it was between 250-300 mg/dl in 18 per cent and between 350-400 mg/dl in 24 per cent of the rats. In conclusion it appears that long term VIT regenerates pancreatic beta-cells of IDD rats and possibly by improving their secretory functions it relieves diabetes mellitus.

Effects of vanadyl sulphate on glucose homeostasis in severe diabetes induced by streptozotocin in rats.

Rats made severely diabetic by an i.v. injection of 50-55 mg/kg streptozotocin (STZ), 15 days later showed blood glucose > 500 mg/dl, quadrupled daily water intake and plasma insulin of 14 +/- 3 microU/ml, about 25 per cent that of normal rats. Subsequently, these rats in two groups, received 0.5-1 mg/ml vanadyl sulphate in base solution (vanadyl) orally (Group I) and base solution containing 50 mEq/1 NaCl (Group II). Since 90 days of vanadyl therapy could not decrease blood glucose of group I (420 +/- 10 mg/dl) to normal levels, euglycaemia was achieved for a period of two months by intraperitoneal (i.p.) injection of NPH insulin. The required daily doses of insulin in vanadyl-treated rats of group I (8 +/- 1 U/kg/day) were only 8 per cent of those in group II animals (103 +/- 7 U/kg/day). In conclusion, it seems that vanadyl per se cannot induce normoglycaemia in diabetic rats with very low plasma insulin levels, but can augment the sensitivity of peripheral tissues to insulin.